One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,6)(4,5)(7,8)(9,10)(11,13)(12,14)(15,16)(25,26,28,32,29,31,35,38)(27,30,34,36,33,37,39,40)(2,5)(6,8)(9,11,12,15)(10,13,14,16)(17,18)(19,22)(20,21)(23,24)(25,27)(26,30)(28,34)(29,33)(31,37)(32,36)(35,39)(38,40)(1,3,4,7)(2,6,5,8)(10,14)(13,16)(18,21)(22,24)(3,7)(6,8)(17,19,20,23)(18,22,21,24)(26,31)(27,33)(32,38)(34,39)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.